In a field-effect transistor (FET), the doping type and the doping concentration of the source and drain regions are different from the doping type and doping concentration of the channel region. Thus, PN junctions are formed between the source region and the channel region, and between the drain region and the channel region. By applying bias voltages on the source region, the drain and the channel region, the FET is turned on, or turned off. For power electronic devices, vertical junction FETs (JFETs) are usually used as switching devices.
However, with the continuous development of semiconductor technology, the technical node has gradually decreased; and the critical dimension of the semiconductor device has also become smaller and smaller. The threshold voltage-drift effect and the increase of the leakage-current have affected the performance of the power semiconductor devices more and more. Thus, the JFETs are unable to satisfy the requirements of power semiconductor devices; and the performance of the power semiconductor devices is significantly affected.
The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems.